Hearing and apparatus



Jul -5, 938.- W PENN 2,123,119

HEARING AID APPARATUS Filed June 26, 1936 A- V/9\0UTPUT g 70 I Pennmutant- ,1938") Y z,1z3,119

UNITED STATES 'PATENTfoi-rica 1 $5.31??? $113121) T? 'i V This inventionrelates to a new and'improved flieted, and may be adjusted. and alteredfrom p mtus used in aidinghearing and more partime to time to suit. theneeds of the user, as his v ticularly toa method and device forobtaining a needs may change.

J frequency selective amplifier for use in aiding This is accomplishedby providing a trans- 5 hearing of the partially deaf. An object of thisformer or electromagnetic; device, having one or 5 invention is toprovide anapparatus that may more secondary windings to which arecoupled v be used-in aiding hearing and which is adapted. devices'whichselect the frequencies or bands of to amplify selected frequencies.frequencies which aregto be attenuated. B y al- Another object of thisinvention is to provide tering or ch e ra risti of these a hearing aidapparatus in which the frequency latter devices, the frequencies orbands of fre- '10 response characteristic may be controlled byquenciesto be att n fl are an Where means of an electromagnetic device,such asa it is desired to change Only O q e cy band transformer or achoke coil, the frequency charwhich is to be attenuated, this maylikewise be acteristics of which may be'controlled or adjusted. one t eqal a l ty.

13' Still another object of this. invention is to Further'details ofthis invention warm ap- 15 provide a hearing aid apparatus with anelectroparent tqihose skilled in the art to which it magnetic devicewhich. is'adapted to controlthe relates, from the followingspecification and the frequency response of said apparatus and whichdrawing, in which, briefly, Figure 1 illustrates an is adapted toattenuate certain predetermined embodiment ofthisinventionfFigures 2 and2a 3 selected audio frequencies depending upon the. illustrateanotherembodiment of this invention hearing deficiencies of the partially deafuser. and Figure} shows an electrical network em- A further object ofthis invention is to provide ployed for the purpose of explaining theoperahearing aid amplifying apparatus adap'tedto -attion of thisinvention. l l tenuate certain selected audio frequencies or Referringto Fig 1 of the drawing n il. I

b d audio frequencie depending n t .,reference numeral lildesignates asound pick-up 25 hearing deficiencies of the hard of hearing or .1(ital/ice micmphoner Sound recmd partiallydeaf user. reproducing device,and the like, connected to j Still a further object of this invention isto 1 e p ma of a ans rme f a d to a providq hearing i device adapted tused suitable source of current supply H. Thesec by pe'rs'qns gflflctedth partial d f said ondary ii of the transformer is connected to 80hearing aid device employing an electromagnetic .thegrid electr de' t thl tric discharge dev lapparatus having a plurality of windings, each I!and to a C battery'lB which is connected to of said windingsbeing'adapted to function to the cathode of the electric dischargedevice. A a attenuatecertain frequencies or bands offresuitable'sourcejofcurrent supply 11 is provided I quenciegito whichth hard of hearing" user 1s for energizing the anode of the electricdischarge the most sensitive. 3 device amplifier 15. The anode of thedevice I Other and further objects of this invention ll-is connected tothe impedance winding l8 will be apparent to thoseskilled in the art towlileh'isshunted across the output terminals l9 4a which it relates fromthe following specification of the amplifier. -'I'iie impedancifl isprovided 40 u .and theclaims." I "with two additional circuits coupledto' thecore' r In accordance iwith thisinvention I provide a thereofforthe purpose of altering the frequency circuit arrangement adapted tobe used in hearcharacteristic of this'impedance device. These ,ing aidapparatus, employing an electromagnetic "additional windings aredesignated as 20 and 2| 4 ,device, such as a transformer, in which oneor and they may be wound xon the core 22 of the more windings areemployed to attenuate one impedance device "in various ways depending ormore frequenciesgor bands of frequencies the upon theresults desired.'{Ihese' windings 20 and ..level of which it is desired to reduce. V -2imay be wound over the winding I8 so as to 'I 'he :apparatusof my invetion is simple in' be concentrictherewith and maybe movable with #0construction and may beeasil and readily made respect to the winding Itin, order to he posi- 5 i to fulfil the needs of persons aiiiictedwithpartioned over different sections'of-the latter windtial deafness. Theapparatus-of my invention i'ngr The-terminals of the windings 20 and-2|maybe made to attenuate certain frequencies are connected tojsuitableimpedances 24 and or bands-of frequencies, dependingupon thenarespectively. The. .nature,.--of these impedances 65- ture of thedeafness with which the user is at will govern the effective impedancebetween the v mutual impedance thereto, the response frequencycharacteristic of the hearing aid apparatusof this invention can becontrolled as desired. Where convenient and desirable to obtain furthervariation in 'the frequency response characteristic, an additionalimpedance or impedancesmay be connected to the taps Ila and Ilb of theimpedance II, or the output circuit directly.

In the circuit diagram shown in Figure 1 the may be connected to thesetaps anode current of the electric dischargedevice.

amplifier ll obtained from the source of. current supply I! passesthrough the winding It or through this winding. and the output deviceconnected to the terminals it, This current may be prevented fromflowing through the impedance winding II by connecting resistance acrossthis winding between the source of current supply I! and the anode ofthe device I 5 and by inserting a suitable blocking condenser betweenthis resistance and one of the terminals of the winding II. This willprevent the anode current derived from the source I! from passingthrough the winding I I in cases where it is decurrent from magsired toprevent this anode netizing the core of this impedance device. q

The windings II and II may be wound each with a different number ofturns or each with a different inductance. Each of these windings may betuned by means of suitable condensers to be resonant to certain audiofrequencies and to absorb power at said frequencies from the circuit ofthe winding ll. Thus the frequency characteristic of the hearing aiddevice may be varied, d pending upon the characteristics of theimpedance device. Furthermore the resonance characteristics ofthecircuits of the windings II and Il may be broadened if desired in one orboth of these windings to cover a relatively broad band of frequencies,by connecting a resistance of suitable size in series with each of thesewindings.

In Figures 2 and 2a I have shown the impedance winding I. connectedbetween the microphone or other soimd pick-up device and a reproducingdevice 28,

tric discharge device amplifier.

winding II or by moving thecorell, to obtain the desired frequencyresponse characteristic.

The operation of the he'aringaid 'ofthis invention. in cases where thewindings I, II, and II oi the impedance device are closely coupled maybe determined from the following when considered with the equivalentelectrical network shown in Figure 3.

l'br the general'case of a transformer with a between primary andsecondary windings the without theuse of an elec- The operationimpedance looking into the primary winding of the device is Z 21X, is=i+ Z.+J(XI F)=RI+ In the above equation:

Ri=l=tesistance of primary winding.

Ri=Resistance of secondary circuit including resistance component ofload.

X1=Reactance of primary winding.

X:=Reactance of secondary winding.

X=Total reactance of secondary circuit.

The equation shows that for any given coefficient of coupling k theimpedance looking into the, primary is a function of the load impedanceconnected to the secondary. The impedance Z1:

. here corresponds to the impedance designated as Z; in the case of theclosely coupled transformer.

For a closely coupled transformer, Z1 is equal to the quantity 1ndivided by n: squared, times Z2. Where m is the number of turns in theprimary of the device It and m is the number of turns in the secondaryof this device. Z: is

' the impedance in ohms of the impedance device connected to theaforesaid secondary. If Z2 is a pure resistance then the effect ofconnecting it across the winding 1:: is in effect the same as shuntingthe output device of impedance Zr with a resistance. If Z: is aninductance 1-, for example, the eflect of connecting it across thewinding m is the same as shunting 2;- with an. inductance equal to thequantity m divided by m squared, times n. On the other hand, if Z: is acondenser the eifect of connecting it across the winding m is the sameas shunting Zr with a condenser equal to the quantity as divided by 1&1squared, times 0, c being the value of the condenser. If the transformerhas more than two windings the impedance looking into any winding,called for convenience the primary winding, of a transformer having Nwindings is equal to the self-impedance Z, of the primary windingmultiplied by the product of all the load impedances Zs, Zs, Zs, Zn towhich the other or secondary windings are connected, and divided by thesum of the products of the various self impedances of the secondarywindings Z2,

' Zs, Z4.-Za and the various load impedances with the self impedance ofimpedance pedance of winding ll, ,of winding ll, Z: is winding II, andZ. and

Marge 3 55's. Ess

impedance Zs, the power loss introduced into the circuit by theeffective shunt impedance Z5 may be determined from the followingequation which gives the power loss in decibels.

What I claim and desire to secure by Letters Patent of the United Statesis as follows:

1. A device foraiding hearing by attenuating frequencies to which a userof the device is normally sensitive, comprising aninput device, anoutput device. an electromagnetic frequency attenuating device having awinding shunted across said output device and eletromagnetic means foraltering the frequency attenuating characteristics of said frequencyattenuating device, said last mentioned means including one or moreimpedance circuits coupled to. said fre-,

quency attenuating device for the purpose of introducing losses equaltoin decibels, where 2,; is the effective impedance in the circuit ofsaid input device, Zr is the impedance of said output device and Z5 isthe effective shunt impedance of said frequency attenuating device, saidlosses being introduced at frequencies determined by the characteristicsof said attenuating device for reducing the response of the hearing aidat these predetermined fre-' quencies to which the user is normallysensitive to a level substantially below the normal response of thehearing aid the remaining frequenciea:

2. A device for aiding hearing by attenuating frequencies to which auser of the device is'normally sensitive, comprising: a. sound pick-upand translating device, a vacuum tube amplifier having an input and anoutput circuit, means for connecting saidsound pick-up and translatingdevice to said amplifier input circuit, a sound reproducing deviceconnected to said amplifier output circuit, a frequency selectiveattenuating device comprising a main winding connected across saidreproducing device, said frequency attenuating device having at leasttwo auxiliary windings coupled together, an impedance device connectedto each of said auxiliary windings for altering the frequencycharacteristics of said attenuatingdevice, said impedance devicesconnected to' said auxiliary windings of said attenuating device beingadjusted so that said attenuating device will absorb power from thecircuit of said amplifier and' fr'om said sound reproducing device atfrequencies determined by the characteristics of said impedance devicesand said windings for the purpose of reducing the response of thehearing aid at these predetermined frequencies, to which the user isnormally sensitive, to a level substantially below the normal responseof the hearing aid to the remaining frequencies. w

3. A device for aiding hearing by attenuating frequencies to which auser of the device is nor-- mally sensitive, comprising: a sound pick-upand translating device, a' vacuum tube amplifier having an input circuitand an output circuit, means for connecting said sound pick-up andtranslating device to said amplifier input circuit, a sound reproducingdevice connectedto said output circuit, a frequency attenuating devicehaving a main winding connected across said sound reproducing device anda pair of auxiliary windings coupled to said main winding, animpedance'device connected to each of said auxiliary windings,

each of said impedance devices forming a power' absorbing circuit withthe auxiliary winding connected thereto, having predetermined frequencycharacteristics such that the hearing aid device may be adjusted to meetthe deficiencies of partially deaf persons by selecting impedancedevicesof such frequency characteristics thataudio frequencies to which thepartial] deaf person is normally sensitivewill be at enuated when theselected impedance devicesareconnectedto'said auxiliarfwindings.

, wILLmM norm.

